Zebra Mussel Monitoring Program

Zebra mussel on a piece of wood

Zebra mussels are spreading to lakes and rivers in the Midwest. These small invasive mussels attach to hard surfaces in lakes and rivers killing native mussels, limiting recreational activities, clogging water supply pipes, and competing with larval fish for food. You can provide important help tracking their distribution in Minnesota by spending a few minutes monitoring the lake or river where you live without any specialized equipment. Early detection for zebra mussels is important in protecting your property and Minnesota's water resources.

How can you monitor for zebra mussels?

In the late summer or fall when removing equipment from lakes or rivers:

Zebra mussels with a quarter to show scale

  1. Visually inspect hard surfaces for zebra mussels such as docks, dock floats and supports, swimming platforms, boats, motors, anchors, and any objects that have been in the lake or river for the summer. Check areas where zebra mussels may be attached, such as trim tabs, rubber gaskets, grooves along the keel of pontoon boats, and sailboat centerboards. During early infestations, zebra mussels are likely to be small (1/4-1/2 inch long) and the number attached on any object is likely to be low. You can also examine rocks and other hard surfaces along the shoreline and in shallow water, especially near water accesses.
  2. Complete and send in a online Volunteer Monitor Report Form by November 1st each year. Send in the report whether or not you found zebra mussels.

What else can you do? (optional activities):

Make your own monitoring device. Hang a PVC pipe , brick or cinder block under a shady spot of your dock (zebra mussels tend to avoid direct sunlight) in the summer to monitor for zebra mussels. Suspend the object as deep as possible at the end of your dock, keeping it at least one foot above the bottom. Examine the monitoring object, and add these observations to the Volunteer Monitor Report Form.